protected internal DoubleRange GetYRange(double x1, double y1, double x2, double y2, double x3, double y3, double x4, double y4)
{
DoubleRange range = DoubleRange.Union(new double[] { y1, y2, y3, y4 });
double cy = 3 * (y2 - y1);
double by = 3 * (y3 - y3) - cy;
double ay = y4 - y1 - by - cy;
double r1, r2;
if (ChartMath.SolveQuadraticEquation(3 * ay, 2 * by, cy, out r1, out r2))
{
if (r1 >= 0 && r1 <= 1)
{
double y = ay * r1 * r1 * r1 + by * r1 * r1 + cy * r1 + y1;
range = DoubleRange.Union(range, y);
}
if (r2 >= 0 && r2 <= 1)
{
double y = ay * r2 * r2 * r2 + by * r2 * r2 + cy * r2 + y1;
range = DoubleRange.Union(range, y);
}
}
return(range);
}
/// <summary>
/// To get the SurfaceHeight for PyramidSeries.
/// </summary>
public static double GetSurfaceHeight(double y, double surface)
{
double r1, r2;
if (ChartMath.SolveQuadraticEquation(1, 2 * y, -surface, out r1, out r2))
{
return(Math.Max(r1, r2));
}
return(double.NaN);
}